


scientifically irrelevant (except in the bedroom)

by abapical



Series: A Series of Incestuous Events [3]
Category: Teen Wolf (TV)
Genre: Alpha/Beta/Omega Dynamics, Barebacking, Father/Son Incest, Incest, M/M, Mating Cycles/In Heat, Multi, Stiles is 14, Underage Sex
Language: English
Status: Completed
Published: 2014-05-19
Updated: 2014-05-19
Packaged: 2018-01-25 19:13:07
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 8,609
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1659320
Author URL: https://archiveofourown.org/users/abapical/pseuds/abapical
Summary: <blockquote class="userstuff">
              <p>This heat match isn't going quite the way Derek expected.</p>
            </blockquote>





	scientifically irrelevant (except in the bedroom)

**Author's Note:**

> So real life is a pain in the ass and this part is literally nothing but porn, but it exists! And it's not 12K of porn like it originally was! Thank you again to anyone who enjoyed the previous parts (and all the props in the world to you if you're still around).

Derek recovers as fast as possible.

He has to give himself a mental shake for faltering at all. Stiles is steadily sinking deeper into his heat, surely he has no idea how he sounded - he just meant his dad helped him in a purely fatherly way. Got him water, made sure he was comfortable, maybe gave him a few toys to get through it. _Surely_.

Stiles is starting to tug at his shirt, so Derek shucks it off, pretending not to notice the way Stiles gapes at him. What he _does_ acknowledge is the way Stiles sets his jaw and starts undoing his own jeans.

"You're lucky he was there," Derek murmurs against his sweaty temple, and tilts in for another kiss. He's getting a little addicted to the taste of this kid, and no one wants to spend their heat talking about their parents.

But Stiles just gives a soft whine, trying to tilt his hips and kick free of his pants. "It hurt too much, I couldn't do it by myself."

And once again, Derek pauses for a split second before he catches himself. "So he... made it stop hurting," he says, treading carefully.

Stiles can’t actually be saying what it sounds like he’s saying; it goes against everything Derek’s ever learned. The immediate family of an omega isn't supposed to respond to the omega's heat, everyone knows that. The family is supposed to want to _protect_ the omega, not breed them themselves. But Derek’s noticed things about this family that don’t exactly fit the mold. Things like how concerned the sheriff was about selecting an alpha for his son, how he made Derek jump through more hoops than most families would. Derek had just chalked it all up to John being protective on account of his own alpha status and Stiles being so young to be having heats at all. He likes the sheriff, the man clearly just wants to make sure his son is all right.

Stiles moans and rubs one of his soft pink cheeks against Derek’s chest, lashes dropping too low for Derek to see his eyes. "I just--I needed, so he-- _yeah_."

It’s cruel of Derek to try and make him talk when he’s like this, when the scent of arousal rolling off him is so thick it’s dizzying. Stiles' mouth is hanging open, pink and needy like he’s desperate for something inside. Derek obliges, working his tongue in gently until Stiles keens into his mouth and arches his skinny hips up off the bed. 

For a little while, Stiles is content just to cling and be kissed, squirming his body against Derek without a trace of shame. He’s still in his underwear, which is adorably modest and just plain impressive all things considered. Behind the thin cotton, his cock is flushed full and hard and he's _wet_ , already slick all over. Derek knows the scent well. It makes his fangs ache to slide out, makes his eyes roll back and a growl start to build low in his throat, but he hasn't made a name for himself in this business by _not_ being able to control his impulses, so he swallows it down.

Stiles is grinding against him with the artlessness of inexperience, gasping little pleas Derek can't quite make out even with his wolf hearing. When he comes, it's with a sharp cry and his overtaxed body shaking all over. 

He lets Derek stroke down his spine and lay him on his back, gives a jerky nod when Derek hooks a finger into the waistband of his briefs and obligingly lifts his hips so he can pull them off. Derek presses a kiss to the center of his chest. "Doing okay? Was it..." he hesitates, still bothered by what Stiles told him, but trying to sound concerned, rather than crude. "Was it like this when he made you stop hurting?"

Stiles is sprawled with his limbs akimbo, belly damp with sweat and come. He has smooth skin, soft and speckled with moles, and Derek can feel the heat coursing underneath it with every touch. "Mm. Definitely okay." He smiles blearily up at Derek, his cock pulsing another stream of precome when Derek gently slides a finger back to see if Stiles is as ready as he smells.

Derek doesn’t move any further than that, just stroking against his slick little hole with one fingertip. “Can you tell me what it was like last time? It’ll make it easier on both of us if I know what you like.” 

Stiles’ breath is hitching on every inhale. He probably can't for the life of him figure out what Derek is waiting for. "H-he took care of me, I needed it," he croons. "I need it now, please, can you…?"

And Derek’s not here to tease Stiles, so he ignores the questions in his head long enough to start slipping a finger inside him. The kid is begging for it and Derek's job is to say yes, no matter how much he wants to demand an explanation.

When Stiles reaches down and and slips one of his skinny fingers in alongside Derek’s own, they both hiss. He’s wet enough that it goes easily, and judging by the way Stiles whimpers, the stretch is just a pleasant ache. "Feels good... wanted to do this last time."

Derek's mouth goes dry. "Last time?" Stiles has no clue what he’s saying, he _can't_. He's already undulating down onto both their fingers and Derek's other hand comes up to stroke his belly, his cock, instinctually. He wants to make this boy feel incredible, even now, but something is off, something he's got in the corner of his vision but can't quite adjust the focus enough to really see.

"Yeah, my... my first heat?" Stiles says, sounding flustered, like he doesn't understand what Derek is asking. "Wanted to put my fingers in too, I was just too scared."

Derek brain turns a somersault and gets stuck on the word _too_ , which definitely indicates the presence of someone else's fingers.

He really shouldn't be interrogating Stiles _and_ nudging against his prostate simultaneously, but that doesn't mean he can't try. He knows it's wrong, he's playing off Stiles' lowered inhibitions, but he needs to know what he's dealing with. "Was it like this?" he asks, his voice low, rubbing against that sensitive little spot inside him until Stiles sobs for him, hot and leaking. "Did it feel good?"

He's not asking for specifics per se, but at the rate Stiles is going he'll incriminate himself in about ten seconds.

" _Yeah_ , felt really good. He takes good care of me, he made it all better."

Derek can't move. He's supposed to be the calm, in-control one; he's brought Stiles to orgasm once already, he has a finger _inside_ him, and he can't move. 

None of this was his imagination. Stiles means it, he actually _means_ it, and his dad--his dad, the _sheriff_ , the man who seemed so protective of his kid and so invested in making sure Derek was the right choice for him--is just downstairs, white-knuckling his way through the night as Stiles gets seen to. What the hell is Derek supposed to do? Go downstairs and tell the sheriff he can't finish? Try and lecture Stiles about being taken advantage of? Pretend he hasn't put the pieces together and finish helping Stiles through his heat like nothing's amiss?

"I… Stiles, I know it's hard, but I need you to listen to me." He watches Stiles' bleary eyes attempt to focus on his face, and he feels terrible, but this is too important. "Just because something feels good doesn't mean...it doesn't mean..." He can't even get the words out without feeling his gut lurch, and when he tries to draw his hand back Stiles makes the most heartbreaking sound of loss.

"What's wrong?"

Derek's heart falls into pieces. He gathers Stiles close, kisses his forehead, does his best to ignore the panicked edge to his breathing. "He shouldn't have done that to you."

And for a few long, agonizing seconds, Stiles goes absolutely still.

There's a new hint of salt to his scent, but he's not crying, not yet, even though his eyes are wide and bright. Derek's waiting for it, already trying to rehearse what he'll tell the sheriff when he explains this isn't a situation he feels comfortable being involved with. 

"I _needed_ him," Stiles says suddenly, fiercely, which is more surprising to Derek than tears. "It happened too fast and I was scared and I told him I couldn't do it by myself, that's _all_. It wasn't anything bad."

“Stiles--”

"Do you wanna go down there and _ask_ him?" Stiles demands, with all the antagonism of a hissing kitten. Derek's never been a fourteen-year-old omega with a heat that hits like a ton of bricks at least two years before it should, but if he were, he doesn’t think he’d be capable of forming sentences at this point. He can tell how hard Stiles is fighting to keep the tremble out of his voice.

What Derek _is_ capable of is soothing away all sorts of negative emotions. He gets his fingers back at Stiles' hole and carefully rubs there, just placating him a little, so the tension leaches back out of his limbs. "No, I want to ask you," he says, calm as can be while the alarm bells continue in his head. "Has he touched you since then?"

He knows how much the sheriff cares about Stiles, he doesn't need werewolf senses to tell him that. The sheriff probably just couldn't stand to see his son in so much pain, so he made the only choice he could think of. Derek just needs to be _sure_.

Stiles' breath shudders into his lungs, body clamping tight around Derek's fingers when he eases them deeper. "N-no, never. Are you mad at him?" And then his heart rate quickens and he tenses up all over again. "Are you mad at _me_?"

Derek can only imagine what Stiles would have been like the first time, when it caught him by surprise in the middle of the night and the only person he had around was his dad. He does sympathize with the sheriff on that front. Derek hasn't felt this protective over an omega before.

He buries a kiss in the shorn hair at the base of Stiles' neck, draws him in against his chest, and slowly, slowly works his fingers in him until Stiles is whimpering and spilling precome all over both their stomachs. "You must trust your dad a lot.”

And Stiles just nods frantically, clenching so hard around Derek's knuckles it makes him grit his teeth. Derek can't make out everything he says, it's only half-intelligible thanks to the way Stiles' breaths are hitching, but he gets the gist: _please don't be mad, it was so scary and we didn't know what to do, I just needed it_. 

There's more than just trust happening here. Even before Derek knew this, he knew Stiles and his dad were closer than most human families. Stiles is shaking against him--Derek is impressed he hasn't come again, but it also occurs to him the poor kid might be so worried it's keeping him suspended right on the edge. It’s not fair to press Stiles for more, not when he’s like this. So he smooths his back, kisses his soft cheeks and murmurs, "It's okay, baby, go ahead and come. It's okay." 

And Stiles does.

The orgasm doesn't really calm him down; he's getting to that point where coming just makes his need plateau. Derek slows his fingers when Stiles stops twitching, but Stiles just spreads his legs wider and whines, "Don't, don't stop," like he's afraid Derek is going to leave again.

Derek doesn't say a thing, just rolls them so Stiles is securely snuggled between him and the mattress, then kisses him until he feels some of the nervousness taper off. As much as Derek wants to press Stiles' thighs up and knot his hot little hole until the headboard cracks the wall, what Stiles really needs right now is reassurance. He isn’t as socially developed as an omega having heats would normally be, so in a way this is just as new to Derek as it is to Stiles.

"'s nice," Stiles mumbles, petting clumsily at whatever parts of Derek he can reach. Then he goes absolutely rigid. Derek braces himself. "Oh my god, you're wearing pants. It's like a zillion degrees, dude, why would you do that? This is serious, what are you _laughing_ at?"

After that, the time blurs together.

Derek pushes all thoughts on the sheriff into the darkest recesses of his mind and focuses on nothing but making Stiles' heat as painless as possible. Stiles doesn't know how to kiss, but he's a mouthy little thing and catches on fast. Derek learns just how sensitive his nipples are, just how ticklish his ribs are, and the first time he slides his mouth over him he has to force down another growl. That's really not something you do around nervous virgins, but Stiles is seriously trying his powers of restraint. The taste of him, the way he cries out and scrabbles at Derek's hair and practically arches off the bed trying to fuck himself deeper into Derek's mouth, all of it has Derek grasping for shreds of self-control. And later, when Stiles is curiously licking the taste of himself off Derek's lips, he lets his claws ease out just for a second.

By the time Derek has three fingers inside him, Stiles is on his belly, letting out tiny gasps each time Derek's fingers push into him, and so slick it's streaking the insides of his thighs. When Derek asks if he can taste him, Stiles clenches obscenely around his knuckles utters a moan that his dad can probably hear all the way downstairs.

Derek doesn't mind it when Stiles' knees give out and he collapses full length onto the bedding, he just spreads him open with his thumbs and licks right back into him. He can't keep Stiles empty for long, though, he has to push two fingers back into him when he starts giving those high little whimpers that Derek's already started to translate.

Stiles sounds almost surprised when he comes. He very well might be, he's been drifting a sea of overstimulation for so long. And he still whines when Derek stops, tries to get a knee under himself, push his ass up a little higher. A drop of wetness works its way out of his hole, trailing over his balls, and Derek's tongue is there right away, licking it up.

“How,” Stiles groans, “am I still technically a virgin?” and Derek has to pull away to laugh.

“Is that a hint?”

“I don’t need to hint.” Stiles flops onto his back and looks at him with steady eyes even though there’s a blush shading his cheeks. “I’m ready.”

Derek kisses his temple. “You’re sure?”

“Pretty sure, yeah,” Stiles says, in what sounds like the verbal equivalent of an eyeroll.

His face falls a bit when Derek sets the condoms on the nightstand, and Derek doesn't get it at first, he just helps him drink a little more water and goes back to snuggling him, waiting for his heat to crest again. He's completely thrown when Stiles pauses in the midst of sucking experimental hickeys into his neck just to watch them heal and asks, "Do you _have_ to wear one?"

Derek’s been heat matching on and off for the past three years, he knows how to control his reactions, and he _still_ gapes at him.

“I...I just mean, you can’t...I’m not gonna catch anything from you, you’re a freaking werewolf.”

He’s flushing even pinker and squirming against the bed, kneading his fingers into the sheets like a cat. Derek can’t even breathe without being dizzied by the scent of him. This isn’t helping him get a handle on his gaping. “Stiles, that’s not the--”

“You’re on birth control, I saw that in your file,” Stiles interrupts. “I mean, if you’re not gonna transmit anything _anyway_...”

Derek’s never had anyone try to argue with him about this; omegas just tend to be grateful there's a warm body there to help them through the heat at all. Nearly every contract includes words about using condoms, and even the ones that don't, Derek ends up using them anyway just out of habit. “It’s...it’s standard procedure,” he chokes out. “Your dad signed the contract, we can’t just disregard everything we agreed to.”

Derek has come already, all over Stiles' belly with both their hands wrapped tight around him. That was another thing he didn't expect, but Stiles _really_ wanted to see him come, and preferably be a part of making it happen. He'd just squirmed into his arms, slipped one of his hands around Derek's cock, and kept whispering how much he wanted to feel him inside him, making him even wetter. At the time, Derek hadn’t taken that literally.

“So go revise the contract, _then_ knot me,” Stiles sighs, squeezing his eyes closed as if he’s trying to will his body into quiescence. “Fast would be good, just saying.” 

Derek is still thrown by the way he can say these things and look so innocent even though he knows very well how uninhibited a heat can make someone. “I don’t know if that’s--”

“Just go talk to him. He’s two seconds away.”

“I don’t think it’s a good idea."

“I don’t think I care,” Stiles says amiably. “I’ll be right here, it’s okay. Where am I gonna go?”

By the time Derek makes it to the top of the stairs, he’s a wreck. He's never had to do anything like this; interacting with anyone but the omega in question during a heat just isn’t done. And now he smells like sex even though he gave himself a quick wipedown and threw on an extra shirt and pair of boxers, and he can hardly make it downstairs without tripping. 

Then there’s the sheriff, who looks like he's barely reining in some particularly violent urges as he sees Derek appear at the foot of the stairs.

"You just _left him?_ " he finally demands, staring at Derek like he's lost his mind. "You left him up there like that?"

Derek swallows. "He--we--one of us needed to talk to you and he's not really, um, fit to move that much."

"He's _fine_ ," Derek quickly adds before the sheriff can assume the worst -- John, he’s supposed to be John, even though Derek can’t see him as anything but a sheriff now. "It's taken a lot out of him, that's all."

Talking to the father of the omega you're fucking is hard enough, but having to inform him Stiles wants to revise part of his contract while trying not to think about everything Stiles told him about that first heat… it’s not the most awkward thing Derek’s ever done, but it’s close. 

And he must be taking too long about it because Stiles yells downstairs, in a voice that’s equal parts exasperation and sexual frustration, "Dad, just tell him he doesn't have to wear a condom, okay?"

John very, very staunchly doesn’t look away from Derek’s face, but Derek can hear the hammer of his pulse.

" _He's a werewolf_ ," Stiles hollers helpfully. 

When neither of them responds, he follows up with a shaky, " _Please_ , daddy."

And John's brows arch just a bit, his heart rate ticks up just a bit, but Derek doesn't look away either.

"Is, ah, is that okay with you?" he asks, as politely as he can, even though he can tell John is dying to leap the stairs three at a time and make sure his son is okay. "Do you want to see him first? If you wanted to ask him anything, or make sure..." 

The words just tumble out of him. He knows it's a risky thing to say, that most parents would recoil at the idea of setting foot in the room where their kid has been getting ravished for the past few hours, but the sheriff is not most people and the Stilinskis, Derek is learning, are not like most families. 

This has to be torture for John, the least Derek can do is offer to let him see that Stiles is doing just fine. Derek is still trying to digest everything and not blurt out _he told me you helped him before_ but John looks so honestly concerned about Stiles, it's hard for Derek to picture him making his kid's first heat anything but the gentlest experience possible.

Derek could never wrap his head entirely around the concept of this guy actually hurting his son in any way, but it's nearly as tough to wrap his head around the alternative. Maybe Stiles is just too young to grasp the difference, and John really was just helping him the only way he knew how. John probably just wants to make sure Stiles is intact, he can't blame him for that.

“Stiles? We’re both coming up, okay?” 

He hears a reedy _yeah_ from Stiles as they go back upstairs, which he assumes means Stiles is at least making _some_ effort to look decent. Instead, he pushes open the door and finds Stiles writhing on two of his own fingers, head tipped back and mouth parted. 

Derek’s torn between pouncing on him and marching the sheriff right back downstairs. He's felt how tightly Stiles clenches around his fingers, he's heard him sob when he comes. What he really wants is to crawl into bed with him and lick every last smear of precome from his smooth little stomach, ease his fingers out of himself, and press his own back inside instead. He can’t, though, not with his father in the room.

John, against all logic, doesn’t even seem to notice. "You doing okay, kiddo?" 

Stiles curls his toes into the sheets, pushes his fingers a little deeper. Derek feels like he should look away, but he can’t. "Yeah, I'm okay, just...please, _please_ say yes?"

It should be easy for Derek to write John’s response off as concern and overprotectiveness. But he’s standing there smelling repressed arousal radiating from this little omega's dad, trying to tell himself Stiles' heat scent is so overpowering it would make _anyone_ want him and he just can’t quite make himself believe it.

"Yeah," John is saying. "Anything you need, it's okay. We're gonna get you through this." 

He turns his gaze on Derek, looking like he’s about lay down an ultimatum about his medical records all being in order or else, but Stiles heaves a shuddery breath, pressing a hand below his navel like he can feel the push and thrust of his fingers inside himself there. "Love you, daddy."

Derek goes towards the bed as the sheriff starts to retreat towards the door, but instead of reaching for him or upturning his face for a kiss, Stiles' eyes go wide and the first word out of his mouth is, " _Dad_."

Derek doesn't think he's heard him right at first, but Stiles looks almost scared, and he's still staring right at the sheriff. "Daddy, don't go, you don't need to go."

It’s on the tip of Derek’s tongue to say, “Yeah, Stiles, he kind of does," because he's not sure if he's going to be able to fulfill his contract with an audience, particularly not one made up of the omega's _father_. But looking at Stiles' worried face, he doesn’t know how the fuck anyone can ever deny him anything.

He's saved from having to speak up because the sheriff turns around, jaw tight. "I'll be just downstairs. You're doing so well, buddy, Derek's taking such good care of you."

And Stiles arches into the hand Derek's been unconsciously stroking down his chest, lashes flitting against his cheeks. "Yeah, but so did you."

Derek can't even look up. Should pretend to be shocked? Act like he didn’t hear? He decides the best thing to do is give Stiles his full attention, so he shucks off his shirt, slides back onto the bed, and kisses him before he can say anything else. Reaches down to gently grip his wrist and ease it back, so slowly Stiles keens against his mouth at the loss, then just as slowly presses two of his own fingers right back in. 

Stiles is already panting from the sweet, slick stretch of it, spreading his thighs even more and mouthing blindly at whatever bare skin he can find. But even then, heat-drunk and desperate, he's still coherent enough to slit his eyes open and groan, "Daddy, _please_ , I need you too."

Derek is really going to have to think of renegotiating his fee.

At the same time, he can't really blame the sheriff for not wanting to walk away from this. Stiles is so sweet and he's already rolling his hips down, trying to take even more of Derek into him. "Knot me, I can take it, _c’mon_."

He sounds like he's been screaming for hours, his voice is so strained. He's starting to burn up again and Derek can't deny him a request like that now. The last thing he wants is for Stiles to start getting anxious again. It's _awful_ when Stiles is anxious, it gets Derek's hackles up.

This also means he's going to be getting naked in front of Stiles' dad, but the sheriff hasn't seemed to catch on to anything but how desperate Stiles is right now. When he tentatively ventures to the side of the bed and cups a palm to the back of Stiles' head, Stiles gasps so sharply it sounds painful but Derek swears he can actually _smell_ the tension go down.

It's also notable that the touch coincides with a particularly hard clench on his fingers. Stiles has been getting slicker and slicker the whole time his dad's been in the room, and Derek could almost have passed it off as his heat nearing its peak until now.

Derek is definitely, definitely renegotiating his fee.

His heart still goes out to Stiles, even now. He's just a kid, a kid who shouldn't have to be dealing with such an adult thing yet. There's still baby fat evident in the soft flesh of his ass, his stomach, his cheeks, and even though there are patches of hair under his arms and a line starting to darken low on his belly, he's so fucking overwhelmed and young that all Derek can think is that he needs to make this good for him. "We've got you," he murmurs against the rim of Stiles' ear, letting his teeth graze just to feel him shiver again. "We're right here, baby, we just need you to relax. Do you think you can take another finger before you take my knot?"

The sheriff is rubbing little circles against his scalp with his fingertips, whispering to him that he's done such a good job, he just needs to be patient a little longer, he's not quite ready yet. But Stiles gives a broken-off groan and tightens around his fingers so intensely Derek hisses through his teeth. " _Am_ , 'm ready, I can do it, Derek, just come _on_."

Derek nuzzles his cheek and resolutely doesn’t look at John. “Turn over?”

Stiles only has so much muscle coordination left, so it's really Derek gently turning him over, but his body knows what it needs and he arches up for him even though it makes his thighs tremble.

Derek drapes himself along Stiles' back, just resting there for a minute to let him absorb the touch and see if he still wants this. But Stiles only squirms and reaches for his father again, trying to pull him closer. 

John looks up, locking eyes with Derek, and Derek doesn’t know what the hell comes over him, but he nods. He nods and he doesn’t look away and then John is easing onto the edge of the bed just enough to draw Stiles' head into his lap. 

This is seriously happening and Derek can’t even think of a reason why it shouldn’t anymore.

He tries to go slow. When he splays a hand at the small of his back and presses the head of his cock against him, he holds back as much as he can. He doesn't want to rip the kid apart, but Stiles is actually _crying_ now, Derek can smell it as the tears spill down Stiles' cheeks and soak into the sheriff's jeans. He’s been with enough heat-addled omegas that he can tell Stiles isn't upset because of pain, but because he isn't full enough and his body wants it so much he’s rutting against the mattress. Derek's never had so much trouble keeping his wolf traits in check with an omega, and it's literally never been more important to keep it all at bay, what with the omega's father sitting three inches away. He wants to snarl and let his fangs out, pin Stiles down and fuck into him until he’s knotted his tight little ass so hard they can’t even imagine what it’s like to be separate anymore. 

Instead, he confines himself to uttering a low, soft, decidedly un-human growl against Stiles' nape while he pushes into him.

And that’s all it takes. It turns out Stiles _really_ likes werewolves.

He convulses himself apart the instant Derek shoves the rest of the way inside him and Derek doesn't actually _mean_ to make eye contact with John again when he lifts his head from where he's been leaving slow, sucking kisses all over Stiles' nape. But he does, vision gone hard and wolf-sharp and he wants to kick himself when John’s mouth falls open because he knows his eyes are red. He’s not used to losing even this tiny fragment of control of himself, it almost defies logic that the sheriff isn't horrified and ripping his kid away from the thing that's possessing him.

Through it all, he's still rolling his hips in a smooth, steady rhythm, milking Stiles' orgasm out of him until he's trembling against the sheets and the sheriff alike. And John still isn’t looking away from Derek's face, even though he's still gripping Stiles' hand, thumbing the tears from his cheek.

The next thing Derek does is gather Stiles up in his arms and carefully maneuver them until they're on their sides. He's gentle about it, trying to reassure both Stiles and John without actually using words, since he doesn’t trust his command of them, not now. His body starts to stiffen, and he hears Stiles' cry before he even registers his own knot swelling, locking them together. He's never done this before, never fucked an omega without a condom, never heard anything like the moan Stiles utters when Derek starts to spill inside him.

Derek can’t bear to look at John again, not with his fangs itching to slide down, not with his knot flushed and swollen, plugging Stiles full.

Stiles' heart is racing, but he sighs like he’s completely at peace with the world. Derek's keeping his face hidden in Stiles' nape, but his hands never stop stroking long, slow sweeps all down Stiles' body, feeling it lax and at ease for the first time.

John’s voice is hoarse. "Doing okay there, kiddo? Do you feel better?"

Stiles reaches up to paw at his arm, kitten-weak. " _Daddy_. Feels so _good_ , daddy."

Then, after a beat, he mumbles, "Mmm, can we keep him?"

Derek actually laughs. And maybe blushes a little, but he knows the sheriff will never tell.

Normally he would tuck himself around his omega and try to get some sleep while he can, but John is still right there, stroking Stiles' head and looking at him with a fond little smile. Stiles' heat isn't over, but it'll be a while before he's ready to go again. He needs a nap at least, and he’s already started to hum drowsily and lean heavily against Derek’s chest, even though he’s still clenching around Derek's cock like he’s trying to work it deeper inside him.

Derek just isn't sure how he's supposed to deal with this period of time. His knot will go down in a bit, but there's no protocol for what comes next and he can’t exactly get up and leave right now. And when it does go down, should he pull out as soon as possible and give them some privacy? That seems wrong. He’s used to staying inside his omega even then, since it can be stressful for virgins to have to lie there and be empty while their heat builds up again.

"Um,” he ventures, “he's cooled down some and his heart rate's started to get a little slower.”

John just nods. “Thanks." 

And how much is Derek supposed to read into that? Thanks for...knotting his son? Knotting his son and letting him be part of it? For knowing about Stiles’ first heat and not having a breakdown? John must know by now that Stiles let _something_ slip about that first heat.

But it’s cozy lying spooned up behind Stiles and his thoughts are already starting to blur--it's been a long day for him too. 

He doesn’t know how long he sleeps, hardly knows when he wakes. All that registers at first is Stiles sighing and squirming back against him. Derek’s knot has gone down, but Stiles seems to have no intention of letting Derek slip out of him. And John is still there, cradling his son’s head and letting him rut against the mattress as best he can, murmuring at him to let Derek get his rest.

Derek knows he should be severely weirded out by this family, but he mostly just finds it sweet how much they care about each other. Maybe he's so flooded with endorphins he can't view this objectively. That's probably it.

“How’re you doing?” John asks, and Stiles gives a moan. 

"Good. _Full_.”

Derek has no idea how John is even functioning right now. This is hands down the longest sustained arousal he’s ever smelled on anyone who wasn't an omega in heat.

Then Derek opens his eyes just as Stiles murmurs, “I'm getting what I need, but you're not," and immediately wishes he could close them and pretend to be asleep again. 

John is already grimacing at Derek apologetically, like _this_ is the weirdest thing that's happened.

And it’s not that Derek hasn’t started to feel some sympathy for the poor sheriff and his predicament, he just hadn't counted on Stiles _actually bringing it up_.

He mouths at Stiles’ nape, runs a hand down his body until Stiles curves up and sighs his name so beautifully Derek's ready to count this as a flawless diversion. Any inhibitions he had about touching Stiles in front of John have officially fallen by the wayside. It’s still not until Stiles is face down and dozing in the wake of another orgasm that Derek decides he should probably address this thing with John, since he can’t just go on ignoring it. 

He’s still not sure what to make of him. John’s been so careful and attentive with Stiles all this time. And even though Derek can smell the arousal radiating from him, the sheriff is still fully dressed and hasn’t once acknowledged it himself. So he lets the minutes tick by, until Stiles is breathing deeply with his mouth slack against a pillow and his limbs splayed wide, as if he’s trying to absorb as much of the sheets’ coolness as he can. Derek is smoothing a hand over his back without conscious intent, just knowing he isn’t ready to give up touching this omega, when he looks over at where the sheriff is still holding one of his loosely clasped hands.

“You got him through it before, didn't you.”

It’s really not a question. He already knows the truth, but he needs to see the sheriff’s reaction.

John’s cheeks turn almost as red as his son’s. “We didn't plan on it. I never thought it would happen so early.”

“Stiles told me it came on fast.”

For a long time, John doesn’t answer, just rubs his thumb against the back of Stiles' hand. “I was gonna make him handle it alone,” he says at last, like the words are choking him. “He was in his room for maybe an hour before he started crying, saying it hurt. You don't let your kid go on hurting like that.”

Derek knows there's more to it than that. He can smell arousal that’s been radiating from John ever since he stepped into the room full of Stiles' scent. But he does believe that no matter what the situation, the sheriff's top priority is Stiles' happiness. It's patently obvious that Stiles wants this attention from his father, and it's just as obvious that John is guilty about wanting to give it to him.

"It must've been tough," Derek says, looking down at Stiles, all flushed and soft. "Heat hits him hard."

"He was begging me to-- to... but I didn't," the sheriff says, "You were his first. I only did what I had to. He didn't know what he was saying, I couldn't--"

"He loves you," Derek cuts him off. He can't let John call himself a monster when this obviously isn't one-sided in the least. "I think he knows what he wants."

The sheriff rubs his free hand over his face. “He’s going to need so much goddamn therapy.”

Derek really didn’t expect to be having this conversation while his come is dripping out of Stiles' body, not that he expected to be having it at _all_ when John called him at work and told him he’d be picking Stiles up early from school. He wants to run a finger down the cleft of Stiles' ass, slip it inside to keep him filled while he sleeps, but the sheriff sounds like he hates himself and Derek can’t let that go.

“I’m from a werewolf family,” he says simply. “I didn’t sleep at all the night my little sister was conceived. And when I went into my uncle’s room to tell him, he didn’t read me a story or tell me I was going to have a little brother or sister next year, he told me about the birds and the bees instead. In detail. When I was _seven_.” He still guilt trips Peter about that, or would if Peter had any regrets whatsoever. Peter can be kind of an asshole; he never did have much patience for beating around the bush.

The sheriff’s mouth ticks up at the corner, just a touch. “And you grew up to get into heat matching.”

“Stiles is lucky to have you, and he's going to be _fine_.” He’s not actually sure how much he believes this, especially if the sheriff is so intent on blaming himself, but he knows John can’t smell the doubt on him.

It's almost too quiet for even werewolf senses to hear when John covers his face again and sighs, “I shouldn’t have done it." 

Derek's hand pauses between Stiles' shoulder blades. John is looking directly at him now, his brow lined. "I shouldn’t even have been there, I should have taken him to a clinic as soon as I knew what was going on.”

Derek never thought he'd end up wanting to give the sheriff a bone-crushing hug and squeeze all the self-doubt out of him, since he mostly went into this hoping the sheriff wouldn't pull a shotgun on him for looking at his kid funny or something. He can't believe he even thought for a second that this guy might have forced himself on Stiles.

John gives a wry, brittle laugh. "So I guess we should go over just how much I'll owe you for this, huh?" 

And Derek grins in spite of himself because he's had the same thought multiple times by now. But somehow, collecting his due doesn't seem like that big of a deal anymore. Stiles' situation runs deeper than he'd realized and he doesn't think this is the sort of thing you can put a price on. He doesn't think he could possibly ask for more money, that would just make both of them feel like they inflicted some sort of hardship on him. Stiles was just so much happier with his dad present, and that made Derek happier. The best alphas mirror their omegas emotions during a heat, his mother taught him that long ago. 

Stiles is still dead to the world and looking like a debauched angel, so he misses it when Derek slides up the bed and carefully gives the sheriff's shoulder a squeeze. "I mean it, you don't need to worry about anything."

He needs to be very clear on this or John is going to be berating himself for the rest of his life. And Derek knows he smells like he's just bathed himself in Stiles' scent and John isn't exactly firing on all cylinders here; he’s not about to overwhelm him any more on top of that.

“Did you, um, wanna lie down?” John's been sitting up against the headboard all this time, where he can easily stroke Stiles' head or clasp his hands, and Derek still doesn’t actually expect him to do his best impression of a Stiles faceplant. Still, his default reaction is to provide physical contact even though the sheriff isn't his omega. Sometimes even alphas need an alpha. And that's the thing -- until Stiles was eight, John actually had one.

"You want to take care of Stiles, we all know that. He just wants to take care of you too." He can't tell the sheriff to feel a certain way, but he can give him a little reassurance even if it makes his breathing falter and his heartbeat give a little hitch. 

"You know, I didn't hire you to take care of _me_."

Derek shrugs. "Yeah, but you shouldn't have to pay _anyone_ to take care of you.”

"It's good you're here," John manages after a minute. If Derek shifts a bit, John’s nose is nearly brushing his cheek. "It's really good you're here."

He's shaking, so slightly that John may not even notice it himself, but Derek can feel it when he rests a hand on his shoulder. Derek's never been with anyone but omegas, so he doesn't quite know how to do this, he just has this urge to _comfort_ right now. He’s never really thought too hard about his preferences; even before he got into heat matching he'd gravitated towards omegas. He's a little surprised at how natural everything feels now, but John needs someone there and Derek can do that without a hitch.

He gives John a few minutes to get his bearings, can't help noticing the way he shifts a little closer just like Stiles does. Derek knows he's taking a huge risk when he asks John if he can kiss him--he's already rattled and trembling ever so slightly--but the sheriff has been nosing against his neck and cheek and breathing him in like he needs Derek's scent to live. 

"Definitely not paying you enough," the sheriff mutters. 

And Derek takes that as a yes, so he gives a soft growl against John's jaw and goes for it.

John melts into kisses the way Stiles does, just completely commits. Derek's never kissed another alpha before, there's a little more pushback, but it's really not so different. A prickle of heat washes over him when realizes he probably tastes like Stiles.

He’s not used to this. The omegas he sees are teenagers still learning what feels good, but John presses his hands to his back and urges him in with the surety of someone who knows exactly what he wants, even if he hasn't allowed himself to have it for a long time. 

Stiles is still splayed out beside them, dead to the world, but things start to escalate when Derek gets a hand under John’s shirt and it's really just a matter of time. Derek can’t even remember why he should try to hold back. “Is this what you need?” he blurts out even though it's painfully obvious, but he wants to hear John say it. He's not going to just assume anything here.

John is gripping his hair with one hand and clutching him close with the other. All that comes out of his mouth is a strangled groan, but that’s more than enough to go on. Derek has his pants open and a careful hand on him in no time flat.

And that’s when Stiles wakes up.

Derek knows the instant it happens but he still can’t pull away. Stiles’ senses are sharper during a heat, he could probably smell what was going on before he was even fully awake. He's almost afraid to say anything, because John is kind of under a spell right now and he obviously needs this, but he might freeze up again if he knows Stiles is watching. Stiles, with his huge eyes and open mouth, who probably still thinks this is just a fever dream.

Derek is still hardwired to respond when his omega needs him, but when he tries to turn over and bundle Stiles back into his arms, Stiles plasters himself against his back and practically shoves him towards John again. 

There's a split second where John looks guilty, like he's stolen Derek's attention away from Stiles, but Stiles is busy cinching his arms around Derek's middle, rubbing his face against his shoulder blade. "He feels so good, doesn't he, daddy?"

Derek’s breath hisses through his teeth too loudly for him to notice whether Stiles gets an answer.

John is only going to last a couple more seconds anyway. Just the novelty of someone else's touch, of Derek murmuring that he feels good and then kissing him slow and easy with his mouth that tastes the way Stiles smells. It doesn’t take much more than that.

Derek's never felt someone else's knot before. He doesn't know why he expected it to be strange, but it isn't. It's difficult to parse what he's feeling, but there's something intensely satisfying about feeling that swell in his fingers, watching such a powerful alpha fall to pieces for him.

John clings just like Stiles when he comes, clutching at Derek's shoulders, his whole body going tense. His groan is deeper, rougher around the edges than any noise Stiles could ever make, but there's no huge difference. John needs this almost as sharply as his son does.

Stiles' resolve snaps soon after that. This is the first time all evening he’s has woken up without having some part of Derek already inside him, the need is rolling off him in waves, it's honestly impressive that he's been able to hold back long enough to let Derek take care of his father. 

Derek still has John’s come on his fingers when Stiles clambers on top of him, gritting, “ _More_.”

He nearly loses it just from that when Derek teases a fingertip against his hole. He’s squirming down against Derek's cock already, whimpering when Derek presses against him a little and more come drips out of his hole. It makes Derek groan through gritted teeth, and fuck, his father is right _there_. Derek expects John to come to his senses and realize they’ve finally crossed the line, but he just looks sleepy and rumpled, and the furrow between his eyebrows has finally disappeared. He looks _happier_ , against all odds.

“Dad--” Stiles chokes out. He’s arching up so much it's probably making his spine ache. "Daddy, _please_ , need you."

To Derek’s amazement, John smooths a hand down his sweat-damp back, over his ass. Stiles makes a low, startled sound and Derek doesn’t need to check to know with absolute certainty that John just worked a finger inside him. He’s murmuring to him, things Derek can hardly make out over the shudder of his own breath, things about how he knows this isn’t easy, how proud he is of him. 

Stiles really does sob then and John immediately freezes, looking at him with concerned eyes and his brow starting to furrow again. Stiles’ pulse gives a panicked spike and he scrambles to grip John’s hand. "Dad, don't stop, stay in me, I want it." 

Derek tilts his head to face him, trying to offer what comfort he can,and the proximity makes Stiles go in for a kiss. His kisses are open-mouthed and messy, all broken up with gasps while he’s clenching around his father’s fingers.

“Tell Derek what you need, kiddo,” John says softly. “Go on, we’ve got you.”

Stiles is too worked up to do more than whimper against his lips. "Need you inside me, Derek.” He’s clutching Derek's neck with one hand and pawing at John with the other. "Need your knot, _please_."

John has to pull his fingers out then, which tears the most heartbreaking sound from Stiles' throat. His body tenses up all over again but John keeps his fingers there, just resting at the edge of Stiles' hole, long enough to hold him open, guide Derek inside him, so he never really has to be empty.

When Derek slides into him, he has to guide him with both hands on his hips, since Stiles is too uncoordinated to do much more than try to rub against Derek's stomach. He’s got one hand clawed against John’s chest, hard enough to make him wince, but John’s voice is steady when he brushes a kiss to Stiles' cheek and tries to soothe him. "Shhh. Take it easy, buddy, you're gonna be just fine."

He sounds so sure that it makes Derek want to believe it, that they’ll work Stiles through his heat together and everything will be fine, that it won’t be strained or awkward when the dust settles. Even though he’s only contracted for a single heat, he doesn’t want to leave Stiles and John in an even more precarious state than he found them.

And yeah, he’s still aware it’s pretty weird that he’s in this situation to begin with, but he’s also amazed by how much Stiles and John seem to… to _complete_ each other. It’s not like anything Derek's ever seen before and, deep down, he can admit it’s disappointing he won’t get to see Stiles like this again. He was so selfishly happy when Stiles asked John if they could keep him. Even if it's not feasible, it was a sweet thing to say. Derek’s never really felt needed the way the Stilinskis need him right now, like he's not just a body. Most heat matching contracts will include a bit about the encounter being a one-off so no mate bonds are formed, that kind of thing. He hasn’t seriously considered trying to revise that with a client before.

By the time Stiles’ body is sated and snug around Derek’s knot, they’re all exhausted. Derek and John help him drink another bottle of water, then collapse back down with him wrapped up between them. Derek can’t even find the presence of mind to wonder what it’s going to be like when Stiles' heat pheromones aren’t driving them all insane. It’s been a tumultuous evening for all of them.

But since he can’t stay awake long enough to be worried, he nuzzles his face into Stiles' nape and falls asleep.


End file.
